Heater recommendations, South Florida

[dcaton]

Recently bought a house in the Vero Beach, Florida area. Pool is approx. 11,000 gallons, in-ground. We're not here most of the summer when a heater is unnecessary. Running in the pool helps my wife's arthritis so we'd like to extend the usable season as long as possible.

The pool would be heated continuously (or at least for the duration of the usable season, whatever that turns out to be), it wouldn't be fired up just on weekends, etc. Would like to maintain the water temp in the mid-80's for most of the winter, although it wouldn't be a big deal if we had to shut it off for a month or two if we get a cold snap (below 70 ).

We don't have natural gas and I really don't want to go to the trouble and expense of burying a propane tank, so I think a HP is the only viable option.

I was looking at the Raypak Crosswind 65-I. 61,000 BTUs. Next biggest unit I could find is a 90,000 BTU Hayward, about $1,000 more. I know this is a long-term investment and don't want to end up getting something underpowered, but I don't want to waste money on capacity I don't really need.

Would greatly appreciate any advice, especially from someone in this general area or similar climate. It can go down into the 50's or occasionally the 40's but even if it does it generally doesn't last more than a few weeks. Most of the time it's at least in the mid 70's.

Thanks!

 

[ajw22]

There is no substitute for BTUs.

HP BTU output is based on 80F temperature and 80% humidity. In colder weather you will get less BTU output.

Get the largest HP your budget and electrical panel can handle.

 

[dcaton]

Get the largest HP your budget and electrical panel can handle.

Electrical capacity isn't a problem, and in the grand scheme of things, none of these units are going to put us on welfare for the rest of our lives. I don't want to spend more than necessary though (or not spend enough and be disappointed), but at some point I'd think there would be diminishing returns.

These are prices from one distributor's site, I'm sure there are more options out there:

61K = $3000 (.049/BTU)
90K = $4100 (.045/BTU)
100K = $4300 (.042/BTU)
119K = $4500 (.037/BTU)
140K = $5000 (.035/BTU)

On a purely cost/BTU basis the larger the capacity the cheaper it is, but at some point it's overkill and I don't know how to determine that point.

Also, is it more energy efficient to run a larger unit for a shorter amount of time, or doesn't it make much difference? I'd think 140K would be a bit overkill, but if it's cheaper to run in the long term then maybe it would make sense. I don't want to overthink this , but it's not a trivial purchase...

 

[ajw22]

The higher the BTUs the deeper into the winter the HP can hold the temperature you desire.

 

[dcaton]

The higher the BTUs the deeper into the winter the HP can hold the temperature you desire.

Yes, thanks but I understand that, but at some point I would be paying for unneeded capacity. I don't know where that point is. Which is why I was hoping someone in this type of climate might be able to say what works (or doesn't) for them.

 

[HermanTX]

It all about how fast or efficient you want your heating to be
1 BTU is the amount of energy to raise temperature of 1 lb of water 1 deg F
With 11k gallons of water, that is 91,630 lbs of water.
With a 90k BTU heater that is about 1 deg F per hour
With a 140k BTU heater that is about 1.5 deg F per hour (Note these numbers need to be adjusted for efficiency so take 80% of the values above)

This then affects how long your heater is on and pulling kwH.

 

[ajw22]

Yes, thanks but I understand that, but at some point I would be paying for unneeded capacity. I don't know where that point is. Which is why I was hoping someone in this type of climate might be able to say what works (or doesn't) for them.

If you can predict the winter temperatures in your area for the next 10 years and the temperature you want to maintain your pool at you can calculate the heater you require.

They all work. The larger HPs work better as the temperature gets cold then the smaller HPs.

If you get the largest HP you will not say to yourself you should have got a larger HP when your pool cannot get to the desired temperature.

 

[ajw22]

It all about how fast or efficient you want your heating to be

It is about how fast, not efficiency.

A larger HP will use more Kw for a shorter period of time then a smaller HP running longer at lower Kw. Their electrical use per BTU will be about the same.

You pay once for the larger BTU HP and then have the flexibility to heat in colder conditions. Efficiency during operation is about the same.

 

[dcaton]

If you can predict the winter temperatures in your area for the next 10 years and the temperature you want to maintain your pool at you can calculate the heater you require.

We just moved about 100 miles north but the climate here isn't significantly different where we were for 30+ years.

So, generally it's in the 70's during the winter months, sometimes in the 80's. It can dip into the 50's or even 40's but those periods usually don't last long and a HP wouldn't do much if anything in those ambient temps anyhow.

 

[dcaton]

Nobody?

 

[JamesW]

Get the UltraTemp 140.

140,000 btu/hr is a best case.

As the weather gets cooler, the performance drops.

This heater should be able to do about 1 degree per hour at 90,000 btu/hr.

UltraTemp® High Performance Pool Heat Pump

Pentair UltraTemp High Performance Pool and Spa Heat Pump is the first heat pump with ozone-friendly refrigerant is also the most efficient and economical.

www.pentair.com

 

[JamesW]

https://www.pentair.com/content/dam/extranet/nam/pentair-pool/residential/heaters/ultratemp/manuals/ultratemp-heat-pump-installation-and-users-guide-en-fr-sp.pdf

 

[wireform]

A solar bubble cover here will be your best friend maintaining temp and holding off evaporation to the cooler ambient air.

 

[dcaton]

Get the UltraTemp 140.

140,000 btu/hr is a best case.

James,

Thanks for the recommendation, I appreciate it, but this is a trade-only unit. I am going to install it myself (I know what I'm doing when it comes to that).

Really think I need a 140K unit in this climate with a 11,000 gallon pool? Looking at $5k for a Hayward or $4750 for a Raypak, although the Raypak warranty doesn't cover DIY installations whereas the Hayward warranty doesn't state that.

Was hoping to keep this around $4k, but that price is only going to get me a 90K Hayward. What's the average lifespan of these guys? It will only run about 7 months of the year, we're away during the summer. I'd hope to get at least 10 years before having to replace. it.

 

[dcaton]

A solar bubble cover here will be your best friend

Yeah, I know but I've already raised that possibility and it has a very low WAF. Depending on how much the heater increases our electric bills, it might be an easier sell down the road. I was going to try one of those water additives that claims to help reduce evaporation, but I've seen mixed reviews on those.

 

[JamesW]

Really think I need a 140K unit in this climate with a 11,000 gallon pool?

I do not know the exact amount of heat required.

I like to add a margin of safety to make sure.

Maybe a smaller unit will work fine, but you need to know exactly how much heat you will need and exactly how much heat a unit will produce under the conditions.

The smaller you go, the more likely it is that you will have an undersized unit that won't meet your needs.

Maybe someone else will have the exact numbers you need to make a more exact choice.

 

[dcaton]

Maybe a smaller unit will work fine, but you need to know exactly how much heat you will need and exactly how much heat a unit will produce under the conditions.

And therein is the problem. I know the pool size and I know the climate. What I don't know is how to calculate the BTU's needed, if there even is such a calculation.

 

[mknauss]

Have you looked at Heat Pump Calculator

 

[dcaton]

Have you looked at Heat Pump Calculator

Yes, and I didn't find it particularly helpful. Every single model shows the swim season from March to September. The swim season down here is May through October without a heater. It's certainly not taking climate into consideration although it asks for my zip code.

The only difference in all of these models is how long it takes to heat water 10 degrees. What I really care about is whether it can maintain a given temp (say, 85) given average daytime temperatures in the low to mid 70's. I wouldn't even care if the heater took a while to compensate for any overnight heat loss. It's not like we need the pool to be heated to an optimal temperature 24/7. If it was at a decent temperature by mid-day, that would certainly be acceptable.

If it was a pair of pants, I'd just buy a couple of different sizes and return the ones that don't fit... I've only got one chance to get this right.

 

[ajw22]

If it was a pair of pants, I'd just buy a couple of different sizes and return the ones that don't fit... I've only got one chance to get this right.

If you can buy only one pair of pants then you buy it too big since you can always take it in to fit but if too small you can’t make it fit well.

That is what many of us has been advising you. Buy the largest HP your budget allows. Having too many BTUs is not a problem. If you have too few BTUs you can’t stretch them to make it fit.

And those liquid covers hardly work. Plan to get a solid pool cover if you are going to run your HP in the cooler months.

Over design to get it right. It only costs you once.